Method and apparatus for transmitting information simultaneously to multiple destinations over shared wireless resources

Abstract

In a method for transmitting data, data intended for each user in a set of users is simultaneously transmitted on a plurality of spatial using common time and frequency resources during a first transmission time interval. At a user, a data stream transmitted is received on a plurality of spatial channels, wherein the plurality of spatial channels share common time and frequency resources during a given transmission interval.

1 . A method for transmitting data from a transmitter to each user in a set of users simultaneously, the method comprising:
 simultaneously transmitting, on a plurality of spatial channels, respective data to each user in the set of users using common time and frequency resources during a first transmission time interval.   
   
   
       2 . The method of  claim 1 , wherein the plurality of spatial channels are user-specific beams formed by electronically weighting a phase and amplitude of each transmit antenna associated with a spatial channel. 
   
   
       3 . The method of  claim 2 , wherein the user-specific beams are formed such that interbeam interference received by each user is reduced. 
   
   
       4 . The method of  claim 3 , wherein the simultaneously transmitting step transmits data to each user over at least one corresponding spatial channel. 
   
   
       5 . The method of  claim 1 , wherein the set of users includes at least a first user, the method further comprising:
 generating at least one beamformed data stream to be transmitted to the first user based on channel information and at least one quality of service metric, the channel information and quality of service metric being associated with the first user, and each of the at least one beamformed data streams including at least a portion of data intended for the first user; and wherein
 the simultaneously transmitting step transmits the at least one beamformed data stream to the first user on at least one of the plurality of spatial channels. 
   
   
   
       6 . The method of  claim 5 , wherein the generating step further comprises:
 demultiplexing a data stream into at least one data substream to be transmitted to the first user; and   processing the at least one data substream to generate the at least one beamformed data stream.   
   
   
       7 . The method of  claim 6 , wherein the demultiplexing step demultiplexes the data stream into at least one frequency band. 
   
   
       8 . The method of  claim 6 , wherein the processing step further comprises:
 modulating the at least one data substream to generate at least one modulated substream; and   beamforming the at least one modulated substream to generate the at least one beamformed data stream.   
   
   
       9 . The method of  claim 6 , further comprising:
 distributing the at least one beamformed data stream among a plurality of antennas, and   combining, for each of a plurality of antennas, the at least one beamformed data stream with at least one other beamformed data stream distributed among the plurality of antennas.   
   
   
       10 . The method of  claim 9 , wherein the at least one other beamformed data stream is associated with another user. 
   
   
       11 . The method of  claim 1 , further comprising:
 selecting, based on at least one performance metric, the set of users and at least one spatial channel on which to transmit data to each user in the set of users, the set of users being selected from a plurality of users requesting service; wherein
 the simultaneously transmitting step transmits data to each user on at least one of the plurality of spatial channels. 
   
   
   
       12 . A method for transmitting data from a transmitter to each user in a set of users, the method comprising:
 first selecting a first set of users and at least one first spatial channel corresponding to each user in the first set of users based on channel information and at least one quality of service metric associated with each user in the first set of users; and   simultaneously transmitting data to each user in the first set of users using common time and frequency resources during a first time interval.   
   
   
       13 . The method of  claim 12 , wherein the first selecting step selects the first set of users and the at least one first spatial channel corresponding to each user using a greedy algorithm. 
   
   
       14 . The method of  claim 12 , further comprising:
 second selecting a second set of users and at least second one spatial channel corresponding to each user in the second set of users based on channel information and at least one quality of service metric associated with each user in the second set of users; and   simultaneously transmitting data to each user in the second set of users during a second time interval; wherein
 the users in the first set of users are different from the second set of users. 
   
   
   
       15 . The method of  claim 14 , wherein the second selecting step selects the second set of users and the at least one second spatial channel corresponding to each user using a greedy algorithm. 
   
   
       16 . The method of  claim 12 , further comprising:
 second selecting a second set of users and at least second one spatial channel corresponding to each user in the second set of users based on channel information and at least one quality of service metric associated with each user in the second set of users; and   simultaneously transmitting data to each user in the second set of users during a second time interval; wherein
 the at least one first spatial channel is different from the at least one second spatial channel. 
   
   
   
       17 . The method of  claim 16 , wherein the second selecting step selects the second set of users and the at least one second spatial channel corresponding to each user using a greedy algorithm. 
   
   
       18 . A method for receiving transmitted data, the method comprising:
 receiving, at a receiver, a data stream transmitted on a plurality of spatial channels, the plurality of spatial channels sharing common time and frequency resources during a transmission interval, at least a first portion of the data stream being received via a first of the plurality of spatial channels, and at least a second portion of the data stream being received via a second of the plurality of spatial channels.   
   
   
       19 . The method of  claim 18 , wherein the receiving step receives the transmitted data at each one of a plurality of receiving antennas. 
   
   
       20 . The method of  claim 18 , wherein the receiving step further comprises:
 processing the received signal to generate an estimate of the transmitted data stream.   
   
   
       21 . The method of  claim 20 , wherein the processing step processes the received signal based on preceding information associated with at least one user to generate the estimate of the transmitted data stream. 
   
   
       22 . The method of  claim 20 , wherein the processing step further comprises:
 processing the received signal to generate a set of modulated data substreams;   demodulating the plurality of modulated data substreams to generate a plurality of data substreams, each of the plurality of data substreams including at least a portion of the transmitted data; and   multiplexing the plurality of data substreams to generate the estimate of the transmitted data.